I'm 17 and lost around 6 stone (84 pounds) in the past year or so. And ever since I've felt really unhealthy. I smoke, but not much. Over the past few months I've been having really bad pains in the top of my left arm, shoulder and chest. Recently these pains have started occurring in my jaw as well. Could I be having mild heart attacks? I'm getting really worried because they are getting worse and worse. I normaly get them during the evening or if I'm relaxing. What is it? What should I do? Thanks.:confused:

I would go to the doctor. Most people experience minor pain before a serious heart attack, although I suspect it is something different. Nevertheless, heart attack is something easy to diagnose and treat, a simple CT scan could give you a definitive answer as to whether you are at risk.

Are they common in someone as young as I am?

No. But, I have met people younger than you who have had deep vein thrombosis, and/or heart attacks, so while not common it is not impossible either. For example, people with my condition (antiphospholid syndrome) could potentially get a DVT, stroke or heart attack at any age.

Really, you need to be checked out because losing weight, and having pains of the kind you are describing are both warning signs. From what you say you KNOW that something is wrong, and if that is the case you'd be an absolute fool not to get it checked out.